Table 1.

Basic characteristics of participants in different categories of tanning bed use

Tanning bed use during high school/collegeTanning bed use at ages 25 to 35
CharacteristicsaNone1 to 2 times/y3 to 5 times/y>6 times/yNone1 to 2 times/y3 to 5 times/y>6 times/y
Mean age at baseline (y)34.832.832.331.635.033.232.732.2
Height, m (SD)1.6 (0.1)1.7 (0.1)1.7 (0.1)1.7 (0.1)1.6 (0.1)1.7 (0.1)1.7 (0.1)1.7 (0.1)
BMI, kg/m (SD)24.0 (5.0)23.5 (4.7)23.4 (4.4)23.4 (4.4)24.0 (5.0)23.3 (4.3)23.6 (4.5)23.6 (4.7)
BMI at age 18, kg/m (SD)21.3 (3.3)21.0 (3.1)20.9 (2.8)20.9 (3.3)21.3 (3.2)21.0 (3.1)21.2 (3.3)21.2 (3.4)
Alcohol consumption at 1991, g/d (SD)3.2 (6.1)3.9 (7.6)4.2 (6.7)3.5 (5.8)3.0 (6.0)4.0 (6.7)3.9 (6.3)4.0 (7.1)
Physical activity, met • h/wk (SD)27.2 (66.6)27.9 (65.1)36.5 (92.7)29.8 (52.1)26.5 (65.0)30.4 (70.2)34.4 (81.6)32.0 (68.5)
Multivitamin use, %45.849.149.348.846.147.847.844.9
Current smoker, %11.813.713.614.611.014.015.518.8
Current oral contraceptive use, %12.113.514.715.611.314.216.016.9
Postmenopausal women, %5.85.94.26.35.37.47.89.6
History of benign breast disease, %29.131.733.031.729.029.632.231.5
Family history of breast cancer, %5.96.67.66.26.05.66.05.8
Age at menarche, y13.4 (1.4)13.5 (1.4)13.5 (1.4)13.4 (1.5)13.4 (1.4)13.4 (1.5)13.5 (1.4)13.4 (1.5)
Age at first birth, y (SD)25.6 (3.9)25.8 (4.4)25.9 (4.4)25.4 (4.7)25.7 (3.9)24.9 (4.2)24.6 (4.4)24.1 (4.3)
Parity among parous women, times1.5 (1.2)1.3 (1.2)1.3 (1.2)1.3 (1.2)1.5 (1.2)1.3 (1.2)1.3 (1.2)1.3 (1.1)
Vitamin D intake at 1991, IU/d (SD)380.2 (249.6)387.0 (256.2)389.5 (258.3)387.5 (259.3)384.5 (249.8)376.2 (260.1)379.4 (254.1)357.8 (261.2)
Outdoor sun exposure, 5+ h/wk (%)
 At high school/college6064.272.375.559.662.665.171
 At ages 25 to 3550.252.959.260.248.754.357.566.4
UV index in the state of residence, 7+ (%)
 At birth18.519.92022.118.22020.523.8
 At age 1518.819.318.721.118.520.120.624.1
 At age 3025.12624.327.225.124.825.227.3

Abbreviation: BMI, body mass index.

  • aOn the basis of the information collected in baseline questionnaire in 1989 unless otherwise specified.